Ok for historical input , since this an antique post..
Making a insertion tool from the hardware store..

if you can find a few appropriate fender washers and some nuts ...
on a long bolt , the deal is getting it in square..
so if there is a way to guide the thing in far enough, and keep it perpendicular... to the tube

a few washers which fit inside the ID of the tube. and you may be OK, they will align things a bit
one on top wide enough to span the end of the steerer
would guide how deep you are pushing the star nut ..

Only need a bout 3/4 of an inch...